Tashkent, Uzbekistan (UzDaily.com) -- A new sub-variant of Covid has managed to make noise in the United States, where it continues to spread rapidly. Several cases have already been reported in the UK. So what do you need to know about XBB.1.5?

What is XBB.1.5?

This is another version of the Omicron coronavirus variant that is now dominant all over the world, which, in turn, appeared at the end of 2021, displacing earlier virus mutations - Alpha, Beta and Delta.

Omicron has spawned many sub-variants that are even more contagious than the original.

It is believed that the symptoms of XBB.1.5 are similar to those of previous versions of Omicron, but it is too early to say for sure. Most people’s symptoms are similar to the common cold.

Is XBB.1.5 more contagious or dangerous than earlier variants?

XBB.1.5 itself is descended from XBB that began circulating in the UK in September 2022, but health authorities have not found sufficient reason to classify it as ‘of concern’.

XBB had a mutation that helped it "breakthrough" the body’s immune defenses, but exactly the same mutation reduced the ability of the virus to enter human cells.

Imperial College London professor Wendy Barclay says that XBB.1.5 has a mutation known to geneticists as F486P, which restores the ability of the virus to enter cells without losing the ability to elude our immune system. This makes it easier for the virus to spread.

According to Barkley, these changes in the genome of the virus can be compared to the rungs of the evolutionary ladder: as the virus develops, it finds new ways to bypass the host’s defense mechanisms.

At the Sanger Institute near Cambridge, geneticists are sequencing at least 5,000 samples of the viral genome every week, trying to keep up with new variants.

According to Ewen Harrison, an employee of the Institute, most likely XBB.1.5 appeared as a result of infection of one of the patients with two different versions of Omicron at once.

“Part of the genome of one virus merged with a fragment of another, and then it began to spread in this form,” he explains.

On Wednesday, the World Health Organization (WHO) confirmed that in terms of growth and spread, the XBB.1.5 variant has more prospects than other viral variants known to scientists so far.

At the same time, WHO emphasizes that there is no reason to consider this sub-option more serious or harmful than the usual Omicron.

The WHO assured that they would closely monitor laboratory tests, hospital data and statistics of XBB.1.5 infections in order to better understand the impact this infection has on those who are sick.

Where is XBB.1.5 distributed?

Experts estimate that more than 40% of new coronavirus infections in the US are caused by XBB.1.5, making it the dominant variant in the country.

Moreover, in early December, it accounted for only 4% of infections, that is, XBB.1.5 quickly overtook previous versions of Omicron.

In recent weeks, the number of hospitalizations due to Covid-19 infection in the United States has begun to rise, and the country’s authorities have again rolled out a program of free testing for the virus.

Are scientists worried about XBB.1.5?

Prof Barkley is not particularly concerned about the spread of a new sub-variant of the virus in the UK, as she says there is no indication that XBB.1.5 will overcome the protection against severe disease that vaccines provide. There is concern about the effect XBB.1.5 has on people at risk, including immunocompromised patients who are less likely to benefit from vaccinations.

Professor Hunter also sees no evidence at this time that the XBB.1.5 could be more dangerous than other Omicron variants. Accordingly, the current option has no more chances to put the patient in the hospital or lead to his death than the others. “The funny thing is that everyone is focused on the possible emergence of new variants in China, and XBB.1.5 appeared in the US,” he notes.

Professor David Heymann of the London School of Hygiene & Tropical Medicine acknowledges that there is still much to be learned about the new variant. However, it is unlikely to cause major problems in countries such as the UK, which have high vaccination rates and a history of previous infection control. What really worries scientists is China, where demand for vaccines has been reduced due to lengthy lockdowns, and immunity to the virus in the majority of the population remains rather weak. "China needs to share clinical information about infected people to see how the variant behaves in an unvaccinated population," Professor Heimann said.